Almost immediately following the Littleton, Colo., incident, the media began pinpointing which sounds and images may have fueled Eric Harris and Dylan Klebold's high school rampage. Among them:

Doom: Harris was reportedly a fan of Doom, a 3-D video game in which players slash and shoot their way through killing rooms with their choice of gruesome weaponry.

South Park: On Tuesday, a friend of the killers was wearing a black T-shirt depicting characters from the Comedy Central cartoon. It features four foul-mouthed third-graders living in a morally bankrupt hick Colorado town. Kenny, one of the kids, is brutally killed in each episode.